Recovering the ability to install an iOS app from macOS

Question

I read about an iOS app and click in Safari (on High Sierra) on a link that takes me to

https://itunes.apple.com/app/some-app-name/id-somenumber?mt=8

I'm expecting some link to install the app, but no such luck. The page says instead:

This app is only available on the App Store for iOS devices.

Searching further I find on the company's homepage a link that takes me to the app on iTunes. As soon as iTunes opens, the phone (iOS 11) starts to sync, but no option to install the app. Exactly the same message

This app is only available on the App Store for iOS devices.

appears again.

I am signed in to the Mac and the iPhone with the same AppleID. How do I recover the option to install an iOS app while I'm in front of my mac?

Update (following Nimesh's answer)

I don't necessarily want to initiate the buy/install action on my mac, but reading reviews and making the decision whether to buy/install is much easier done on the desktop. Afterwards, it would be nice if I don't have to go through the circuitous route of dropping the information (especially when I can't locate a permalink) into Notes/Reminder and pulling that note under iOS.

In any case, aside from all that, can someone confirm that downgrading to 12.6.3 from 12.7.x will not reveal incompatibilities in handling one's music collection?

Answer 1

You must have iTunes 12.7 or later installed on your Mac.

With the release of iTunes 12.7, Apple removed the ability to browse, download or install iOS apps via iTunes for macOS/Windows.

In case you wish to browse App Store on your Mac/Windows PC, you can still download the last version of iTunes with App Store built-in (iTunes 12.6.3) via the Apple Support article, Deploy apps in a business environment with iTunes.